In recent years, development of navigation systems based on e.g. GPS and digital maps has been, and increasingly is, growing rapidly. The accuracy of GPS receivers has improved, and at the same time, the road coverage of digital maps has been extended and bundled with large amounts of data about the road network, while its accuracy has improved. The accuracy and amount of information contained in digital maps is constantly evolving, offering a large amount of knowledge about the road network.
In addition to road network topography, digital maps may be able to carry large amounts of information describing the characteristics of the road, such as speed limit, number of lanes, curvature, slope, tunnels, lane dividers, traffic signs etc. Accordingly, digital maps may be useful to many in-vehicle applications, such as autonomous driving, active cruise control, vehicle energy management and/or collision mitigation, in that digital map information about the road being driven may be extracted, and potentially presented to the applications.
US 2008/0243378, for instance, discloses a navigation system for a vehicle, including a position sensor, other sensors such as a camera, laser scanner and/or radar, and a digital map comprising records of the vehicle's surrounding objects. The vehicle location is determined, subsequently supporting features such as enhanced driving directions, collision avoidance and/or automatic assisted driving.
However, although US 2008/0243378 enables positioning of the vehicle; in order to exploit the opportunities provided in current and future digital maps to support e.g. active safety applications, improved data accuracy is of most importance.